/golang-style

name: golang-style
description:
  Go conventions specific to this author. Use before writing or editing any Go
  (.go) file.

Go conventions

Where this author deviates from, or tightens, idiomatic Go defaults.

Errors and control flow

• Structure functions so the happy path flows straight down: handle each error

and return early, then continue with the main logic. Main logic never nests inside an `if err == nil` branch.

• Only wrap errors with `%w` if the underlying error should be

exposed.

• Define expected error conditions as package-level sentinel errors

(`var ErrNotFound = errors.New("not found")`) and check them with `errors.Is`, not `==` or string matching.

Go version

Your idea of "current Go" is frozen at your training cutoff and is usually out of sync with the project in both directions. Before writing code, read the `go` directive in `go.mod` and check `go version`, and target the lower of the two.

That drift cuts both ways:

• Newer than you know: a helper you are about to hand-roll may already exist in

`slices`, `maps`, `cmp`, `testing`, or a package you have never heard of.

• Older than you assume: a feature you treat as ordinary may postdate the `go`

directive and simply not build.

`go doc <pkg>` answers both, but only for the toolchain installed here. To ask about the version the module actually targets, use the pkg.go.dev API — no auth, GET only ([announcement](https://go.dev/blog/pkgsite-api), spec at `https://pkg.go.dev/v1beta/openapi.yaml`):

# Which symbols does a stdlib package have at a specific Go version?
curl -s "https://pkg.go.dev/v1beta/symbols/slices?version=v1.21.0"

# Current Go release, and any release candidate in flight.
curl -s "https://pkg.go.dev/v1beta/versions/std"

# Third-party: latest version, and the symbols it declares.
curl -s "https://pkg.go.dev/v1beta/module/github.com/google/go-cmp"
curl -s "https://pkg.go.dev/v1beta/symbols/github.com/google/go-cmp/cmp"

Release notes are not in the API — fetch https://go.dev/doc/go1.N for a release's changes, or https://go.dev/doc/devel/release for the index.

Formatting

• Maximum line length 120 characters. Break long signatures and `fmt.Errorf`

calls one argument per line.

• Indent with tabs rendered 2 wide.
• Organize imports with `gci`.
• End documentation comments with a period sign.

Comments

Every comment ends with a period, including inline ones inside a function body.

Naming

Never shadow a predeclared identifier with a variable or parameter name — not `new`, `len`, `make`, `copy`, `max`, `min`, `clear`, `any`, `error`, `string`, or any other builtin function, constant, or type. Pick a descriptive name instead: `length` over `len`, `dataCopy` over `copy`.

Sage

If the project has a `.sage` folder (Sage is used), run tasks through the Sage-generated Makefiles rather than invoking `go` directly.